Meituan-Dianping / Meituan-Dianping/Robust

Modify 方法嵌套 Add 方法,导致反射调用 Add 方法失败

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Description

异常类型:app运行时异常,反射Add方法调用失败

手机型号:OnePlus3

手机系统版本:如:Android 8.0

Robust版本:0.4.78

Gradle版本:3.3

系统:Mac

堆栈/日志:

04-11 10:13:34.965 11645-11645/com.zhangdan.app W/System.err: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.lang.reflect.Method.invoke(java.lang.Object, java.lang.Object[])' on a null object reference
04-11 10:13:34.968 11645-11645/com.zhangdan.app W/System.err:     at com.meituan.robust.utils.EnhancedRobustUtils.invokeReflectMethod(EnhancedRobustUtils.java:34)
04-11 10:13:34.969 11645-11645/com.zhangdan.app W/System.err:     at com.meituan.robust.patch.MeFragmentPatch.initView(MeFragmentPatch.java:115)
04-11 10:13:34.971 11645-11645/com.zhangdan.app W/System.err:     at com.meituan.robust.patch.MeFragmentPatch.RobustPublicinitView(Unknown Source:0)
04-11 10:13:34.972 11645-11645/com.zhangdan.app W/System.err:     at com.meituan.robust.patch.MeFragmentPatchControl.accessDispatch(Unknown Source:141)
04-11 10:13:34.974 11645-11645/com.zhangdan.app W/System.err:     at com.meituan.robust.PatchProxy.accessDispatch(PatchProxy.java:94)
04-11 10:13:34.975 11645-11645/com.zhangdan.app W/System.err:     at com.meituan.robust.PatchProxy.proxy(PatchProxy.java:44)
04-11 10:13:34.977 11645-11645/com.zhangdan.app W/System.err:     at com.zhangdan.app.me.ui.MeFragment.initView(Unknown Source:12)
04-11 10:13:34.978 11645-11645/com.zhangdan.app W/System.err:     at com.zhangdan.app.me.ui.MeFragment.onViewCreated(MeFragment.java:101)

修改方法如下:

    @Modify
    private void initView() {
        Log.d("MeFragment initView", "MeFragment 修复非static方法");
        initRefreshView();
        initConfigItemsView();
        initHeadView();
        Log.d(AddFixCls.getInstance().getRobustTag(), getFixString());
    }

    @Add
    private String getFixString() {
        return "在类中新增非static方法";
    }

其中 AddFixCls 是新增类,调用是没问题的,可以正常调用到,最终问题出在调用 getFixString() 方法上。
反编译patch如下:

patch.class
    private void initView() {
        ...
        obj = (AddFixCls) EnhancedRobustUtils.invokeReflectStaticMethod("getInstance", AddFixCls.class, getRealParameter(new Object[0]), null);
        if (obj == this) {
            obj = ((MeFragmentPatch) obj).originClass;
        }
        String str = (String) EnhancedRobustUtils.invokeReflectMethod("getRobustTag", obj, new Object[0], null, AddFixCls.class);
        Log.d("robust", "invoke  method is       No:  162 getRobustTag");
        if (this == this) {
            obj2 = this.originClass;
        } else {
            MeFragmentPatch meFragmentPatch2 = this;
        }
//问题出在这里,obj2 实际上应该是 patch 类,但是被转成了originClass,去调用新增的 add 方法当然是调用不到的。
        String str2 = (String) EnhancedRobustUtils.invokeReflectMethod("getFixString", obj2, new Object[0], null, MeFragment.class);
        Log.d("robust", "invoke  method is       No:  163 getFixString");
        ((Integer) EnhancedRobustUtils.invokeReflectStaticMethod("d", Log.class, getRealParameter(new Object[]{str, str2}), new Class[]{String.class, String.class})).intValue();
    }

    private String getFixString() {
        return "在类中新增非static方法";
    }

问题出在这里,obj2 实际上应该是 patch 类,但是被转成了originClass,去调用新增的 add 方法当然是调用不到的。

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by tracing the generated patch for the nested @Modify and @Add methods, especially initView and EnhancedRobustUtils.invokeReflectMethod at EnhancedRobustUtils.java:34. Reproduce the case and inspect why getFixString is invoked with the origin object; done means the added method is invoked on the correct patch object without the reported null-method failure.

Written by the indexing model from the issue text.

Assessment

Tech stack
android, java
Domain
mobile-dev
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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